We recently began invoicing via email (beats the cost of postage, faster and, face it - we're a web company so why would we not?).
Customer: I got this invoice in my email...
Customer: Well I need a printed version for accounting to pay it.
Us: Okay - if you use the print function in your email to print out that invoice you'll have a copy to give to the accounting department.
Customer: But I need a printed version, not email...
Us: We are no longer sending out "print" invoices, just via email. Do you have a printer attached to the computer that you receive email on?
Us: Do you know how to print off the email?
Us: Then I suggest you just print the email for accounting.
Customer: But we need a print version...
*sigh* I gave up and printed the email and put in the mail to them, miraculously a payment arrived on schedule.